1. Field of the Invention
The present invention relates to an error indicator indicating an operational error (initial check error) outside by flashing a light emitter, the operational error detected by executing an operational check (initial error check) in a data modulator-demodulator when power is supplied to the data modulator-demodulator. Moreover, the present invention relates to a data modulator-demodulator with a loop back test function as a maintenance function and relates to an indicating method by use of a light emitter.
2. Description of the Related Art
There is an information equipment in which a CPU (Central Processing Unit), a sequencer and the like are installed, and the information equipment executes a self-check regarding whether or not an operational error occurs in an internal circuit and, when an operational error occurs, displays that. Then, for the external display, a display unit is arranged in the information equipment and the display unit is used, and no display unit is arranged in the information equipment and a light emitter (LED (Light Emitting Diode), lamp, or the like) for exclusive use or a light emitter used also as another indicator is used.
However, when a light emitter is used, as mentioned above, there are the following problems. That is, error check items in the information equipment include different things, therefore, it is impossible to specify a kind of an operational error occurrence when indicating that an operational error occurs only by lighting or flashing the light emitter simply. Further, when light emitters of the same number as the error check items are prepared, it becomes possible to specify a kind of an operation error occurrence, however, when plural light emitters are prepared like this, a number of parts increases exceedingly and a hardware scale becomes greater all over the information equipment.
In this respect, it is also possible to vary flashing cycles of light emitters in accordance with kinds of operational errors to make a user know a kind of an operational error occurrence with a light emitter. In this case, however, it is very difficult for the user to distinguish flash cycles of the light emitters and to know a kind of an operational error, unless the user has a reference tool such as a stop watch or is practiced in the operation.
Now, a data modulator-demodulator (modem) converts digital data outputted from a digital terminal equipment (DTE) into an analog signal and transmits the analog signal to a receiving data modulator-demodulator via communication lines, and further converts an analog signal transmitted from a transmitting data modulator-demodulator into digital data, and the digital data is inputted into the DTE.
Conventionally, such a data modulator-demodulator has a loop back test function for checking whether there is a fault in internal data transmission paths therein and/or in data transmission paths to the receiving data modulator-demodulator or not. This loop back test function sets a loop in data paths of the transmitting data modulator-demodulator and/or in those of the receiving data modulator-demodulator, transmits a test pattern from a checker connected to the transmitting data modulator-demodulator and/or from that connected to the receiving data modulator-demodulator, compares the test pattern which returns via the loop with the original test pattern, and judges that a fault occurs in the data transmission data path from the checker to the loop when both patterns are different.
A local loop back test in that a loop is set in the data modulator-demodulator at a self-station and a test pattern is transmitted from the checker connected to the self station, needless to say, starts by a start instruction signal (trigger) inputted from the data modulator-demodulator at the self-station. On the contrary, a remote loop back test in that a loop is set in the data modulator-demodulator at one of the stations and a test pattern is transmitted from the checker connected to other station, starts by inputting a start instruction signal (trigger) into the data modulator-demodulator at the one station and by transmitting a test command from the one station to the other station, or by inputting a start instruction signal (trigger) into the data modulator-demodulator at the other station and by transmitting a test command from the other station to the one station.
In many cases, the data modulator-demodulator has a light emitter (LED: Light Emitting Diode) which lights to show that the loop back test is executed. When the remote loop back test is executed, both the light emitters of the data modulator-demodulator at the transmitting (self) station and at the receiving (other) station light to show that the loop back test is executed therein.
Thus, it is possible to know that the loop back test is currently executed based on the lighting conditions of light emitters, however, it is impossible to know through which data modulator-demodulator a trigger is inputted to start the remote loop back test.